The present invention relates to a transceiver capable of wireless transmission using multiple wireless methods.
The speed of the wireless LAN (Local Area Network) method that is standardized as the IEEE802.11 standard has increased to the transmission speed of 100 Mbps or higher with the advent of IEEE802.11n. To increase the transmission speed, IEEE802.11n allows information to be transmitted in one of two frequency bands per channel: 20 MHz wide channel similar to that available in the existing standards IEEE802.11a/g and 40 MHz wide channel. In this wireless LAN method, two frequency bands, 2.4 GHz and 5 GHz, are available and, especially, many channels are available in the 5 GHz band without a wireless station license (in the description below, wireless communication using the 5 GHz band is called 5 GHz band wireless communication). The description above is included in “IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements Part 11: Wireless LAN Medium Access Control(MAC) and Physical Layer(PHY) Specifications Amendment 5: Enhancements for Higher Throughput”, IEEE Std 802,11n, 2009. In the 5 GHz band, many channels are used also by various types of radar systems, and IEEE802.11h stipulates that 60-second monitoring be performed before using the channels to confirm that radar waves are not being used.
Recently, attention has been paid to the wireless communication method, which uses the millimeter wave band, as a method for implementing the gigabit-class high-speed wireless communication (in the description below, a wireless communication using the millimeter wave band is called a millimeter wave band wireless communication). For example, in Japan, the Ministry of Internal Affairs and Communications allocates a frequency band as wide as 7 GHz, from 59 GHz to 66 GHz, to this wireless communication without wireless station licenses, and study has been conducted on its application.
On the other hand, JP-A-9-8706 discloses a method in which two wireless transmission/reception systems are provided where the line deterioration status is checked and, upon detecting line deterioration, the wireless transmission/reception system is switched from one system to another.